Home News How to understand the Air Quality Index

How to understand the Air Quality Index

by admin
Air Quality Index

In recent days, certain regions of Canada and the US have experienced a significant decline in air quality due to smoke from wildfires in Quebec and Nova Scotia spreading across the continent. The situation has become so severe that New York City now has the worst air quality among major cities worldwide.

To mitigate the dangers of unhealthy air, various states and cities have issued advisories urging people to stay indoors whenever possible. The Environmental Protection Agency’s Air Quality Index (AQI) serves as the basis for these jurisdictions’ decisions. Metropolitan areas with over 350,000 inhabitants are required to report daily air quality data, while other locations do so voluntarily as a public service.

The AQI assesses air quality based on five major pollutants regulated by the Clean Air Act: ozone, particle pollution (also known as particulate matter or PM2.5), carbon monoxide, nitrogen dioxide, and sulfur dioxide. Additionally, the EPA usually provides AQI forecasts for the following day. When it comes to smoke pollution from wildfires, particulate matter becomes the primary concern for air quality.

The EPA compares the AQI to a weather forecast, helping individuals plan their outdoor activities. However, it’s important to note that the AQI doesn’t explicitly disclose which pollutant has the most significant impact on its values at any given time. Instead, the EPA employs a formula to calculate AQI values, taking into account the overall influence of each pollutant.

Subscribe to the BuyTechBlog Deals Newsletter

Receive exclusive deals on consumer electronics directly to your inbox, handpicked by BuyTechBlog’s editorial team. View the latest offers.


By subscribing, you agree to BuyTechBlog’s Terms and Privacy Policy.

The AQI employs a scale ranging from zero to 500 to indicate air quality levels. A reading of 50 or below indicates a green zone, signifying good air quality with minimal to no pollution risks.

When the index falls between 51 and 100, it enters code yellow, representing a moderate cause for concern. In this range, air quality is deemed acceptable, but certain individuals who are “unusually sensitive to air pollution” may experience health risks.

Once the index ranges from 101 to 150, air quality may start to impact “members of sensitive groups.” These groups include individuals with heart or lung diseases, older adults, children, pregnant individuals, and those who spend significant time outdoors. However, the general public is less likely to be affected in orange zones, as stated by the EPA.

When the index surpasses 151, it reaches code red, indicating that “some members of the general public may experience health effects,” and members of sensitive groups may experience more severe health issues.

At code purple (201 to 300), the AQI triggers a health alert, signifying an increased risk of negative health effects for everyone. Once the index reaches 301, it enters code maroon, representing hazardous air quality and a “health warning of emergency conditions” affecting the entire population.

In code orange zones, the EPA advises everyone to engage in light and brief outdoor activities, while individuals from sensitive groups experiencing symptoms should move indoors. In red zones, it is encouraged for everyone to stay indoors if symptoms occur, and sensitive groups should consider relocating all activities indoors.

When the AQI reaches code purple, sensitive groups should avoid all outdoor physical activity, and others should limit their time spent outdoors. In maroon areas, everyone is advised to remain indoors. In cases where PM2.5 levels exceed an AQI value of 500, extra precautions and protective measures should be taken.

According to the EPA, fine particles from smoke can cause issues such as burning eyes, runny noses, and conditions like bronchitis. They can also worsen chronic heart and lung diseases. Those advised to stay indoors due to smoke pollution should aim to maintain clean air inside their residences. The EPA suggests avoiding the use of burning materials like gas stoves, wood fireplaces, and candles, as well as refraining from vacuuming, as it can stir up existing particles indoors.

If you have an air conditioner, the EPA recommends running it with the air intake closed and the filter clean. For those who must go outdoors, wearing a mask capable of filtering out particulate matter can be beneficial.

An interactive map provides information on AQI levels across the US, Canada, and parts of Central America. At the time of writing, certain areas of New York, Pennsylvania, and Ontario are classified as code maroon, indicating hazardous air quality, according to the EPA. Many other regions are under red and purple alerts.

Source: EPA

Frequently Asked Questions (FAQs) about Air Quality Index

What is the Air Quality Index (AQI) and how does it measure air quality?

The Air Quality Index (AQI) is a measurement tool that assesses air quality based on five major pollutants regulated by the Clean Air Act: ozone, particulate matter (PM2.5), carbon monoxide, nitrogen dioxide, and sulfur dioxide. It provides a scale ranging from zero to 500 to indicate the level of air quality, with lower values indicating better air quality and higher values indicating poorer air quality.

What are the different codes in the AQI and what do they mean?

The AQI uses different codes to categorize air quality levels. A green zone (AQI 0-50) signifies good air quality with little to no risk from pollution. A yellow zone (AQI 51-100) indicates moderate concern, while an orange zone (AQI 101-150) may start to impact members of sensitive groups. A red zone (AQI 151-200) suggests health effects for the general public, and a purple zone (AQI 201-300) denotes a health alert. If the AQI reaches 301 or higher, it represents hazardous air quality conditions.

Who is most at risk from poor air quality?

People with heart or lung diseases, older adults, children, pregnant individuals, and those who spend a significant amount of time outdoors are considered more sensitive to the effects of poor air quality. They are more likely to experience health issues when the AQI levels rise, especially in the orange, red, and purple zones.

What can be done to protect oneself from poor air quality?

To protect oneself from poor air quality, it is advised to stay informed about the AQI levels in your area. When the air quality is poor, limit outdoor activities, especially for sensitive groups. Keep indoor air as clean as possible by avoiding the use of burning materials and refraining from activities like vacuuming that stir up particles. Running an air conditioner with a clean filter and closed air intake can help improve indoor air quality. Wearing a mask designed to filter out particulate matter can also be helpful when venturing outdoors.

How does smoke pollution from wildfires impact air quality?

Smoke from wildfires can significantly affect air quality, with particulate matter (PM2.5) being the primary concern. Fine particles in the smoke can cause various health issues, including burning eyes, runny noses, and worsen chronic heart and lung diseases. It is important to take precautions, follow local advisories, and protect oneself from the harmful effects of smoke pollution.

More about Air Quality Index

You may also like


Jane123 June 8, 2023 - 9:21 am

This article is really useful! It tells ya ’bout the Air Quality Index (AQI) ‘n how it measures the air, y’know, based on pollutants. Ya gotta be aware o’ the different codes ‘n health risks involved, especially with them wildfires ‘n particulate matter messin’ things up!

EcoWarrior22 June 8, 2023 - 9:21 am

OMG, air quality is such a big deal right now. This text helps ya understand the AQI ‘n how it works. Gotta stay safe from those pollutants ‘n know the health risks involved, especially if you’re in a code red or purple zone. Take care, everyone!

NatureLover87 June 8, 2023 - 9:21 am

The Air Quality Index (AQI) is a must-know for anyone concerned ’bout air pollution. This text gives ya the lowdown on how it’s measured ‘n what the different codes mean. Stay indoors if the air quality’s bad, folks!

GreenThumb June 8, 2023 - 9:21 am

Whoa, wildfires are messin’ with the air quality in Canada ‘n the US! This text explains the AQI ‘n its impact. Let’s all do our part to reduce pollution ‘n protect our environment. We need cleaner air, peeps!

CleanAirFanatic June 8, 2023 - 9:21 am

Thanks for sharing this article ’bout the AQI! It’s so important to know how pollution affects our health. Remember, folks, keep those air filters clean ‘n stay informed ’bout the air quality in your area. Breathe easy, everyone!


Leave a Comment